6 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



tion can be made. The sediments in the area between Castle 

 Rock and Olequah are stratigraphically below those outcrop- 

 ping between Olequah and Winlock. 



Section between Olequah and Winlock: — Strata of Eocene 

 age outcrop in the banks of Olequah and Stillwater creeks and 

 also along the railway track at many places between Olequah 

 and Winlock. They consist predominately of massive, sandy, 

 clay shales together with grayish brown sandstones contain- 

 ing carbonaceous seams. These materials are of marine, brack- 

 ish and fresh water origin. With the exception of the basal 

 portion of this section, basaltic flows are absent. The basal 

 part involves certain sandstones and basalts outcropping at the 

 town of Olequah. The upper portion of the section is two 

 miles south of the town of Winlock. The actual contact of the 

 upper limit of the Tejon and the overlying Oligocene has not 

 been definitely determined. Four hundred feet south of the 

 last Oligocene outcrop in the banks of Olequah Creek are 

 Eocene shales containing a marine Tejon fauna. It is impos- 

 sible to say whether the two formations are conformable or 

 not. The strata have approximately the same strike, but the 

 dip of the Oligocene is only 2° to the northeast, while that of 

 the Tejon is 27° in the same direction. It is possible that the 

 two formations are conformable but that in the interval of 400 

 feet between them the dip flattens out. 



The lower portion of this section as exposed along Still- 

 water Creek to the southwest of Vader and as far south as Ole- 

 quah is of marine origin. Stratigraphically above, these strata 

 grade into those of brackish water origin and finally into those 

 containing a freshwater fauna. Still higher up in the section 

 they pass back to a brackish water condition and finally to 

 marine. The entire upper portion of the section is a marine 

 deposit. The total thickness of the Eocene section, as meas- 

 ured from Olequah to Winlock, is approximately 4970 feet. 



The following stratigraphic section shows approximately 

 the variations in the lithologic character of the sediments from 

 the base to the top, including a part of the overlying Oligocene. 



